Water sorption and activation energy in polyimide thin films

Abstract

The water sorption behavior and the activation energy were investigated for various chemical structure polyimide thin films; BPDA-PDA, BPDA-ODA, PMDA-ODA, and 6FDA-ODA. The activation energy for the water diffusion varied in the range of 5.53 to 9.27kcal/mol, and was in the increasing order: BPDA-PDA < BPDA-ODA < PMDA-ODA < 6FDA-ODA. BPDA-PDA and BPDA-ODA polyimide films showed relatively well-ordered morphological structure, which results in relatively low diffusion coefficient and high activation energy. It was found that the diffusion coefficient and the activation energy are significantly related to the in-plane orientation, crystallinity, and packing order in the polyimide thin films. The morphological structure was predominant factors for the water diffusion coefficient and activation energy in the polyimide thin films.